First Texas Case of Anthrax in 2003

Texas officials have detected the state's first case of anthrax for 2003 in a white-tailed deer near Del Rio. "It's not unusual to have a few cases of anthrax in livestock or deer each year in Texas," said Bob Hillman, DVM, state veterinarian and executive director for the Texas Animal Health Commission (TAHC), the state's livestock health regulatory agency.

Anthrax naturally occurs in Texas and other Great Plains states, and horses occasionally get the disease. The anthrax agent is a resilient spore-forming bacterium called Bacillus anthracis, which lives in the ground. Livestock ingest B. anthracis when they forage close to the ground during drought, or when they eat feed grown on infected soil. Horses seem to be more resistant to anthrax than other livestock species, such as sheep or cattle. Naturally occurring anthrax appears in Texas from late June through September and October, and outbreaks end with the start of cooler weather.

Hillman explained that rains spawned by Hurricane Claudette soaked counties around Del Rio, and the moisture was followed by a hot, dry spell. "This weather pattern can trigger the germination of dormant anthrax spores in the ground, causing them to migrate to the surface and contaminate soil and grass."

According to Ralph C. Knowles, DVM, a distinguished life member of the American Association of Equine Practitioners, "Anthrax in the horse is characterized by a high fever (up to 107°F) and a quick death. Rigor mortis is absent or incomplete in an anthrax carcass. Horses frequently have ventral edema (swelling on the underside of the body), are fevered, and are obviously 'sick.' Horse carcasses often have dark blood oozing from the mouth, nostrils, and anus. Diagnosis can be based on these clinical signs, but laboratory confirmation is based on finding B. anthracis in a blood sample or blood culture."

Carla Everett, TAHC information officer, said that most owners vaccinate their horses in areas where the disease is detected. The anthrax livestock vaccine can be purchased through private veterinary practitioners, feed stores, or animal health product distributors, and can be administered by veterinarians or livestock producers. The attenuated live vaccine is given once a year, typically in the spring, and is recommended for livestock residing in or near an outbreak and for animals that will be moved to the area. "Don't administer the vaccine concurrently with antibiotics," said Everett, and she reminded that animals that have been vaccinated should not be sent to slaughter for at least two months. Consult your veterinarian for vaccine recommendations.

Animals on infected premises must be quarantined for at least 10 days after all the livestock have been vaccinated against the disease. This time period allows for any previously exposed animals to die from the disease while the healthy animals develop immunity.

Carcasses of infected animals must be burned thoroughly to prevent anthrax bacteria from leaching into the soil, where it can remain dormant as spores for decades. Proper disposal also prevents wild pigs, coyotes, dogs, or other predators from dragging carcasses and anthrax bacteria from one pasture to another.

Anthrax in Past Years

Everett said that 2001 was a particularly hard anthrax year for Texas livestock. Officials from the Centers for Disease Control visited Texas to get a better idea of actual prevalence, since many livestock owners do not go to the trouble of reporting cases because of the quarantine requirement.

"They surveyed and went door-to-door on these premises, and they saw 35 carcasses of horses and mules on 33 premises, and they saw one donkey (carcass) on one premise (even though only two equine cases had been reported, officially)," said Everett. The CDC found a total of 1,637 animals (in a variety of livestock species) that had died as a result of anthrax.

Hillman said, "Anthrax has been with us for hundreds of years, and while cases are noteworthy, they are not alarming."

All Texas anthrax cases--suspected or laboratory confirmed--must be reported to the TAHC. The regulatory agency operates a 24-hour hotline at 800/550-8242, with state or federal regulatory veterinarians available at all times to take calls and work with private veterinary practitioners and producers. Anthrax cases in other states should be reported to the state veterinarian. Find your state veterinarian here.

About the Author

Stephanie L. Church, Editor-in-Chief, received a B.A. in Journalism and Equestrian Studies from Averett College in Danville, Virginia. A Pony Club and 4-H graduate, her background is in eventing, and she is schooling her recently retired Thoroughbred racehorse, Happy, toward a career in that discipline. She also enjoys traveling, photography, cycling, and cooking in her free time.

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